Render problems are very common in Portugal.
Cement, lime-cement and mud renders are used widely in Portugal virtually every home has some kind of render or another.
Render often hides and even causes many problems for the home owner in Portugal.
Before we can understand the problems associated with render we need to understand what render is used for.
Render is applied to the outside of buildings to keep out the rain and cold drafts and for protecting the structure of the building from the weather.
What it should not be used for is keeping out rising damp or to strengthen a weakly constructed wall.
What are the main problems with render.
Firstly that the mix of ingredients which make up the render could have been wrong in the first place.
Render being applied on the wrong type of surface, previously painted walls or ceilings, structures that are prone to movement or vibration. Used to hold back water ingress.
Washed out Render is often hollow sounding if you tap it with your knuckle. It has allowed the rain and weather to go in behind the render and sit between the house wall and the render. This water slowly leaches a lot of the minerals out of the render which makes it weak and crumbly.
Crazed and Cracked render like this
is caused by the effect of weather and the protective paint being washed off. As a result the rain gets inside the render and with a little freeze thaw activity it eventually goes from a small crack to a fully crazed wall.
The only solution is to chip off the old render and re render again.
A good idea if you are faced with this problem is to cover the external walls of your house with insulation and re render with a modern self coloured acrylic render which will not need painting for ten years.
If you go this route you achieve a dry warm home that will be nice and cool in the winter and cheep to heat in the winter.
“Blown render” is often referred to by people who don’t know what it is.
When render is “Blown” as the trade call it. It is where a section of render has come unstuck from the house wall and sometimes takes on the form of a bulge in the outside surface. There are two causes.
Either the render was put on top of something unsuitable like a painted wall, oil contaminated or movable structure such as shrinking wood or bricks that were not bonded together. Blown render is basically render that has become unstuck and is not supported by the wall as it should be.
To repair it you simply hack it off back to soundly secured render and then re render.
The solution for washed out, crazed, cracked, blown or crumbling render is to remove it. Make the structural repairs that are necessary and replace it with new render or external insulation as described above.
If you are worried about cracks in the render on your home or a home that you want to purchase contact Castelo Construction for a straightforward opinion and advice.